Rotary drilling apparatus



Nov. 9, 1965 F. B. NELSON 3,215,514

ROTARY DRILLING APPARATUS Filed Feb. 23, 1962 2 Sheets-Sheet 1 ZNVENTOR.

ATTORNEY- FRED B. NELSON,

Nov. 9, 1965 Filed Feb. 25, 1962 2 Sheets-Sheet 2 FIG.

INVENTOR.

FRED B. N ELSON A TTORNEY.

United States Patent 3,216,514 ROTARY DRILLING APPARATUS Fred B. Nelson, Chickasaw, Ala., assignor to Norman A. Nelson Filed Feb. 23, 1962, Ser. No. 174,944 3 Claims. (Cl. 175238) This invention relates to the drilling of wells, and more particularly to apparatus for facilitating the drilling of wells by the rotary process.

In the drilling of wells, such as oil and gas wells by the rotary drilling process it is customary to employ a drilling bit attached to the lower end of a tubular drilling string and to circulate drilling mud, or other suitable drilling fluid down through the string and bit and up the annulus of the well bore surrounding the string, to lubricate the bit and carry away cuttings formed during the drilling operation. The drilling mud also serves to form a filter cake or coating on the wall of the well bore to prevent the loss of drilling fluid from the borehole into the surrounding formation when drilling in porous formations.

In carrying out drilling operations of this kind, the hydrostatic pressure exerted by the column of drilling mud in the well bore is usually higher than the pressure of fluid in the formation, so that the net differential pressure is normally from the well bore into the formation at all points in the well bore, even at the location on bottom where the drill bit is cutting, which tends to reduce the generation and removal of cuttings, thus materially, reducing the rate of drilling. The differential between the pressure of the fluid in the bore and that in the formation may also cause the drill collars, or the pipe above the collars, to adhere to the Wall of the bore with suflicient force to hold the string again-st longitudinal movement or rotation in the bore.

Various expedients have been and are being employed to overcome the reduction in drilling rate caused by drilling muds. The use of jet bits to scour the bot-tom of the hole below the bit to dislodge chips is very common. In areas where the formation pressures permit, the use of clear water or air or gas as the drilling fluid results in increased drilling rates because these fluids do not hold the chips down against the bottom of the well bore as effectively as a drilling mud does. The use of gas or clear water is limited to areas where the formation pressures are low and there is no danger of a blow-out. The use of jet type bits with mud is not nearly as effective as using gas or water, but where the increased fluid density, is required to overcome formation pressures, it is one of the few methods available by which the rate of drilling may be successfully increased.

The present invention has for an important object the provision of apparatus for use in the drilling of wells by which the retarding effect on the rate of production of cuttings and drilling rate caused by the hydrostatic pressure of the drilling mud on the formation may be overcome.

Another object of the invention is to provide well drilling apparatus by which the hydrostatic pressure exerted by the drilling fluid on the formation may be reduced at the location where cuttings are being formed to increase the rate of production of the cut-tings and increase drilling rate.

Another object of the invention is the provision in well drilling apparatus of the rotary type, of a drilling bit having a body formed with a passageway through which fluid circulating in the Well may flow, and including means for interrupting the flow of fluid through the passageway in response to rotation of the bit, to periodically reduce the hydrostatic pressure exerted by the fluid on the formation at the location where the bit is in contact with the formation and to create a water hammer eifect on 3,216,514 Patented Nov. 9, 1965 the bit, to increase the downward force exerted by the bit on the formation, to increase the rate of production of cuttings.

A further object of the invention is to provide in well drilling apparatus of the rotary type, the combination with a drilling bit having a circulating fluid passageway therethrough and rotatably mounted cutter elements positioned to be rotated in contact with the bottom of a borehole by rotation of the drilling string, of valve means rotatably mounted on the bit in position to open and close the passageway upon rotation of the valve means and means for rotating the valve means in response to rotational movement of the cutter elements.

The invention also contemplates the provision in well drilling apparatus of the rotary type of means for periodically interrupting the flow of circulating fluid in response to rotational movements of the drilling string to cause repeated reductions in the hydrostatic pressure exerted by the circulating fluid on the formation at the location where production of cuttings is taking place and to cause similar reduction of pressure in the annulus surrounding the drilling string progressively throughout the depth of the well.

The above and other important objects and advantages of the invention will be apparent from a consideration of the following detailed description, reference being had to the annexed drawings, wherein:

FIGURE 1 is a vertical, central, cross-sectional view illustrating a rotary drilling bit and showing a preferred embodiment of the invention;

FIGURE 2 is a cross-sectional view taken along the line 22 of FIGURE 1, looking in the direction indicated by the arrows;

FIGURE 3 is a fragmentary cross-sectional view, similar to that of FIGURE 1 illustrating a modified form of the invention, the fluid flow interrupting mechanism being shown in fluid flow interrupting position;

FIGURE 4 is a cross-sectional view on a somewhat enlarged scale taken along the line 44 of FIGURE 3, looking in the direction indicated by the arrows, showing the fluid flow interrupting mechanism in flow resuming position;

FIGURE 5 is a fragmentary cross-sectional view similar to that of FIGURE 4, illustrating a further modifica tion of the invention with the fluid flow interrupting mechanism in flow interrupting position; and

FIGURE 6 is a view similar to that of FIGURE 5 showing the fluid flow interrupting mechanism of FIG- URE 5 in flow resuming position.

Referring now to the drawings in greater detail, the invention is illustrated herein in connection with its use in the rotary drilling process, in which a drilling bit, gen erally designated by the numeral 10, of the rotary or roller type, is attached to the lower end of a drilling string, not shown, for rotation therewith and to be lowered with the string into the well bore as the drilling of the well progresses. In well drilling apparatus of this kind, it is customary to provide a number of drill collars in the drilling string, immediately above the bit, which drill collars in the drilling string are of somewhat greater external diameter than the external diameter of the drill pipe above, and the drilling bit is of a size to produce a bore of somewhat larger diameter than the drill collars, so that an annulus is provided in the bore surrounding the drilling string, through which a suitable drilling fluid, such as drilling mud, circulated downwardly through the drilling string may flow upwardly to lubricate the drilling bit and carry away the cuttings formed during the drilling operation.

In accordance with the invention the drilling bit 10, as illustrated, in FIGURES 1 and 2 has a generally tubular housing or body 12, of relatively heavy construction provided at its upper end with an externally threaded pin portion 14 for attachment to the lower end of the drilling string and formed at its lower end with an internally enlarged counterbore 16, into which one or more passageways 18 open, which are also in communication with the bore 20 of the bit, to allow the flow of drilling fluid through the bit. A central recess 22 is formed in the bit, opening downwardly into the counterbore 16, into which a central, upwardly extending lug 24 is rotatably extended, which lug forms a bearing for an actuator element or valve member 26 rotatably positioned in the counterbore 16 and which may also have suitable bearing means in the counterbore, such as the ball bearing 17.

The bit is also formed at its lower end with an internally, downwardly flaring, annular face 28, against which conicle, externally toothed cutter elements 30 are seated, which cutters are rotatably mounted on the bit for rotation relative thereto with the teeth of the cutters extending downwardly beyond the lower end of the body 12, in position for engagement with the bottom of the bore to perform a cutting operation on the formation, during the drilling of the well.

Each of the roller cones 30 is formed at its base with a bevel gear 32, whose teeth are positioned for intermeshing engagement with downwardly extending gear teeth 34 formed on the valve member 26 to cause the valve member to be rotated upon rotation of the cutters 30 in contact with the formation in response to rotation of the drilling string. By so constructing the parts that the axis about which the valve member 26 rotates and the axes about which the roller cones 30 rotate, intersect in a common point 36 at the apices of the cones, it will be apparent that when the cones are rotated the gears 32 in intermeshing engagement with the teeth 34, of the valve member 26, will rotate the valve member about its axis.

The valve member 26 has a plate-like central portion 38, which is provided with arcuate openings 48, therethrough which are positioned to move into and out of registration with the passageways 18 as the valve member rotates, to periodically partially or completely interrupt the flow of fluid through the bit. Each of the passageways 18 may also be provided, if desired, with a choke element 42 by which the flow of fluid through the passageway is suitably restricted. Also, the choke elements 42 are forced into engagement with valve member 26 at all times so that an effective seal is assured between the elements.

In carrying out the drilling operation with the apparatus of the invention, constructed as described above, the bit 10 is attached to the lower end of the drilling string, in the usual manner, for rotation therewith, and the drilling string is lowered into the well bore to engage the cutters 30 with the bottom of the bore. Upon rotation of the drilling string with the cutters 30 in contact with the bottom of the bore and a suitable drilling fluid, such as drilling mud, circulating downwardly through the string and upwardly through the annulus in the bore surrounding the string, the cutters will be rotated to perform a drilling action on the formation at the bottom of the bore, and during the drilling operation the valve member 26 will be rotated to cause the flow of the circulating fluid through the bit to be repeatedly interrupted and resumed. When the valve member 26 reaches a position in which the flow of fluid through the bit is interrupted, a sudden downward force or water hammer effect will be exerted on the bit, to increase the pressure of the cutters on the formation, while at the same time there will be a reduction in the hydrostatic pressure exerted by the fluid on the formation at the location where the cuttings are being formed, whereby the cuttings will be more readily broken away from the formation and entrained in the drilling fluid to be carried upwardly therewith through the annulus. This reduction in the hydrostatic pressure, takes place at the bit, when the downward flow of fluid through the bit is interrupted,

will also progress rapidly upwardly along the bore in the annulus to cause a reduction in the differential which may exist between the pressure of the fluid in the bore, and that in the surrounding formation, whereby differential-pressure sticking of the drill collars and drilling string above the bit will be prevented.

The number and position of the openings 40 of the valve member may, of course, be appropriately selected, so that by regulating the speed of rotation of the drilling string, the frequency of interruption of the flow of fluid through the bit may be controlled.

A somewhat different form of the drilling apparatus of the invention is illustrated in FIGURES 3 and 4, wherein the cutter members 30' are each provided at the base with an external, annular beveled face 44, which is positioned to close the passageway 18 of the bit, the cutter member being also formed with one or more external recesses 46, which are positioned to move into and out of communication with the passageway 18 to allow the flow of fluid through the bit periodically as the cutter member rotates. In this form of the apparatus each of the passageways 18 may have a choke, or restriction forming element 42' therein, similar to the choke 42 previously described, but whose lower end portion extends downwardly into the counterbore 16' for engagement with the face 44, so that the bore of the choke will be opened and closed as the cutter member is rotated. In other respects the form of the invention illustrated in FIGURES 3 and 4 is similar to the form illustrated in FIGURES 1 and 2, and functions in a similar manner.

A further modification of the invention is illustrated in FIGURES 5 and 6, wherein each cutter member 30" has an external annular beveled face 44', at its base, and is provided with peripherally spaced recesses for indentations 46, into and out of which the lower end of a valve element 48 may move as the cutter member rotates, which valve element is moveably positioned in the passageway 18' of the bit body 10'. The passageway 18' is formed at its lower end with an internally enlarged counterbore 50, into which the element 48 extends, and the element 48 is formed with an upper end portion 52 of reduced diameter extending upwardly beyond the bottom of the counterbore 58 into the passageway and of smaller diameter than the passageway to allow the downward flow of fluid through the passageway when the ele ment is in open position, and an externally enlarged lower end portion 54, positioned to enter the passageway above the counterbore 50 to substantially close the passageway when the element is in closed position. The lower end of the element 48 may be rounded, as seen in 56, to fit easily into the indentation 46', into contact with the rounded bottom of the indentation, and the bottom of the indentation may have beveled end portions, 58, upon which the lower end of the valve element may ride as the element enters and leaves the indentation.

This modified form of the invention may, in other respects, be similar to the previously described forms, and operates in a similar manner. Thus, upon rotation of the cutter members 30" in contact with the formation, in response to rotation of the drilling string, the valve element 48 will ride along the tapered face 44' and will periodically move into and out of the indentations 46 to open and close the passageway 18' to interrupt the flow of fluid through the bit, whereby a downward water hammer effect will be created on the bit and at the same time a reduction in the hydrostatic pressure exerted by the fluid on the bottom of the bore will result, whereby the improved results of the invention will be obtained.

It should be noted that the hydrostatic pressure relieving effect of the apparatus is not entirely dependent upon the sudden interruption of the flow of fluid through the bit, but may be accomplished by a relatively slow closing and opening of the flow interrupting means. Also, it is not necessary to completely stop the flow of fluid to achieve the effect. The rate of flow of fluid through the bit may, of course, be regulated by the size of the passageway through which the fluid flows and by the pressure of the fluid, and these factors as well as the speed and frequency of flow interruption may be varied to accommodate the apparatus to any operational conditions which may be encountered.

It will thus be seen that the invention provides rotary drilling apparatus embodying fluid flow interrupting mechanism of simple design and rugged construction and by which the rate of penetration of the formation may be subtsantially increased under widely varying conditions of operation.

The invention is disclosed herein in connection with certain specific embodiments of the same, but it will be understood that these are intended only by way of illustration and that various changes can be made in the construction and arrangement of the parts within the spirit and scope of the invention.

Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. In rotary drilling apparatus, the combination with a tubular string adapted to be lowered into a well bore, a drilling bit body attached to the lower end of the string for rotation therewith and cutter means rotatably mounted on the body in position for engagement with the bottom of the bore to perform a cutting operation in response to rotation of the string to form an annulus about the string, said body having a passageway therethrough through which fluid may flow downwardly through the string and upwardly in the annulus, of means rotatably mounted on the body for rotation into and out of a position to restrict the flow of fluid through the body to cause an increase in the downward force exerted by the fluid on the body and means on said cutter means and said rotatable means positioned for coaction to rotate said rotatable means in response to rotational movement of said cutter means.

2. In rotary drilling apparatus, the combination with a tubular string adapted to be lowered into a well bore, a drilling bit body attached to the lower end of the string for rotation therewith and cutter means rotatably mounted on the body in position for engagement with the bottom of the bore to perform a cutting operation in response to rotation of the string to form an annulus about the string, said body having a passageway therethrough through which fluid may flow downwardly through the string and upwardly in the annulus, of means movably mounted on the body for movement into and out of a position to restrict the flow of fluid through said passageway to cause an increase in the downward force exerted by the fluid on the body and means on said movable means and said cutter means positioned for coaction to move said movable means into said position during one portion of the rotational movement of said cutter means and to allow said movable means to move out of said position during another portion of the rotational movement of said cutter means.

3. In rotary drilling apparatus, the combination with a tubular string adapted to be lowered into a well bore, a drilling bit body attached to the lower end of the string for rotation therewith and cutter means rotatably mounted on the body in position for engagement with the bottom of the bore to perform a cutting action in response to rotation of the string to form an annulus about the string, said body having a passageway therethrough through which fluid may flow downwardly through the string and upwardly in the annulus, of means rotatably mounted on the body in position for coaction with the cutter means to open and close the passageway upon rotation of the cutter means to periodically interrupt the flow of fluid through the passageway to produce an increase in the downward force exerted by the fluid on the body and a decrease in the pressure exerted by the fluid on the bottom of the bore to increase the rate of penetration of the bit.

References Cited by the Examiner UNITED STATES PATENTS 1,778,966 10/30 Stokes 319 2,174,102 9/39 Catland 175228 X 2,672,322 3/54 BOdine 17556 2,743,083 4/56 Zublin 17556 2,763,469 9/56 Burls 175--388 X 2,780,438 2/57 Bielstein 17592 2,942,851 6/60 Beck 175-299 X 3,138,213 6/64 Brandon 17556 X CHARLES E. OCONNELL, Primary Examiner. 

1. IN A ROTARY DRILLING APPARATUS, THE COMBINATION WITH A TUBULAR STRING ADAPTED TO BE LOWERED INTO A WELL BORE, A DRILLING BIT BODY ATTACHED TO THE LOWER END OF THE STRING FOR ROTATION THEREWITH AND CUTTER MEANS ROTATABLY MOUNTED ON THE BODY IN POSITION FOR ENGAGEMENT WITH THE BOTTOM ON THE BORE TO PERFORM A CUTTING OPERATION IN RESPONSE TO ROTATION OF THE STRING TO FORM AN ANNULUS ABOUT THE STRING, SAID BODY HAVING A PASSAGEWAY THERETHROUGH THROUGH WHICH FLUID MAY FLOW DOWNWARDLY THROUGH THE STRING AND UPWARDLY IN THE ANNULUS, OF MEANS ROTATABLY MOUNTED ON THE BODY FOR ROTATION INTO AND OUT OF A POSITION TO RESTRICT THE FLOW OF FLUID THROUGH THE BODY TO CAUSE AN INCREASE IN THE DOWNWARD FORCE EXERTED BY THE FLUID ON THE BODY AND MEANS ON SAID CUTTER MEANS AND SAID ROTATABLE MEANS POSITIONED FOR COACTION TO ROTATE SAID ROTATABLE MEANS IN RESPONSE TO ROTATIONAL MOVEMENT OF SAID CUTTER MEANS. 